The present invention relates to medical suction catheters and, in particular, to suction catheters of the dual-lumen type. This invention is related, in part, to Applicant's copending application Ser. No. 441,548, filed May 15, 1995, now U.S. Pat. No. 5,643,230, and entitled "Nasogastric Suction Catheter", and copending application Ser. No. 08/677,390, filed Jul. 9, 1996 and entitled Dual-Lumen Suction Catheter with Multiple Apertures in the Vent Lumen.
The conventional dual-lumen medical suction catheter is specifically designed for the evacuation of the contents of the internal organs of a patient for example, the urinary bladder, the gall bladder, the stomach and the small intestines. Such catheters are used during emergency surgery in trauma cases, during the time the patient is in intensive care, in recovery and, in certain cases, until the patient is released from the hospital.
Since reduced air pressure is present within the suction lumen of the conventional dual-lumen suction catheter, produced by action of the suction pump, it is important that the vent lumen provide air at atmospheric pressure, or above, within the organ of the patient from which the contents are to be evacuated to assure satisfactory operation during the suctioning process.
Due to a number of problems, conventional dual-lumen suction catheters do not always perform in the manner desired. One such problem is the blockage of the suction lumen itself during the suctioning procedures. This occurs when the larger particles within the organ pass through the suction apertures into the suction lumen. If these particles are larger in size and occur in large numbers, the suction lumen becomes blocked and suctioning ceases. It then becomes necessary to flush out the blocked suction lumen, either by air under pressure or by forcing a liquid solution down through the suction lumen from its open proximal end.
Another problem occurs when the vent lumen of the catheter becomes occluded or blocked, thereby preventing air to enter the organ to be evacuated. This blockage effectively arrests the suctioning process. One solution to vent lumen blockage is proposed in U.S. Pat. No. 3,982,540 where an apparatus is disclosed for providing a regulated, small positive air pressure into the open proximal end of the vent lumen. This patent also discloses a modified dual-lumen suction catheter with apertures situated between the vent and suction lumens at the distal end of the catheter to aid in clearing the blockage of suction apertures.
An additional problem, known in the medical arts as gastric reflux, occurs when the contents of the stomach of a patient are forced to enter the vent lumen through a vent aperture or opening by the sudden compression of the walls of the stomach of the patient. This problem occurs when the air pressure within the stomach becomes greater than the normal air pressure within the vent lumen; namely, atmospheric pressure. When gastric reflux occurs, part of the contents of the stomach can be forced up through the vent lumen and out of its open proximal end on to the patient. One simple solution to this problem has been to block the open proximal end of the vent lumen with a plug or cap, although this is frequently overlooked. A proposed solution is suggested in U.S. Pat. No. 4,735,607 wherein a one-way valve is disclosed for insertion into the open proximal end of the vent lumen, the valve allowing air to enter into the vent lumen but preventing air or fluids from escaping.